Improvement in air-pumps



ETTD STATES PATENT OEEIOE.

TEOMAs DOANE, OE BOSTON, MASSACHUSETTS.

IMPROVEMENT lNAlR-PUMPS.

Specification forming part of Letters Patent No. 72,820, dated December31, 1867.

To all whom it may concern:

- Be it known that I, THOMAS DOANE, of Boston, in the county of Suffolkand Gommonwealth of Massachusetts, have invented a new theworking-piston to travel closely up to the outlet-valve, and even tolift it from its seat, thus discharging'every particle of air or gas inthe cylinder, making the pump more effectual in its operation.

lf, as heretofore done, a head containing` both inlet and outlet valvesis screwed solid against the end of the cylinder, then the workingpistoncannot discharge all the air or gas, or other iiuid, because sufficientallowance has to be made for expansion vand contraction for diii'erenttempera-tures, as also, and mainly, for the wear of connecting-rod pinsand journals. The smallest quantity of air or gas remaining in thecylinder' will greatly diminish the effect of the pumps.

To enable others skilled in the arts to make and use my invention, Iwill proceed to describe its construction and operation with referenceto the accompanying drawings, and letters of reference marked thereon.

Figure I is a longitudinal section of the pump. Fig. II is a crosssectionA on line A B. Fig. III is a plan, with cylinder in section,showing the piston at end of outward stroke.

F, in Figs. I and III, is the cylinder of the pump, made of cast-iron,or any other suitable material. A frame or bed-plate, G, is secured tothe front end of the cylinder F, said frame containing the slides forcross-head and box for crank-shaft.

The piston C, provided with a suitable packing, reciprocates in thecylinder in the usual manner by means of piston-rod, connectingrod, andcrank, and may be driven by a belt and pulley, or gearing, or a directattachment of any motor. The piston O is provided with inlet-valves a,a, (four or more or less in num' ber, according to size,) which are keptclosely to their seats by suitable or springs of rubber or othersuitable material. These valves, when closed, form a plain smoothsurface with the front end of the piston.

The cylinder- F is furnished with a head, H, and discharge-pipe, I,which at the same time form a receptacle for the outlet-valve D, made ofbrass or any other suitable material, and

provided with a stem, E, which 'guides the valve in the bearings c c ofthe dischargepipe I. The end of the stem E is provided with a spiralspring, b, or any other suitable spring, which, resting against thesmall cover K, acts against the Washer c on the stem E.,

and keeps the valve D to its seat with a inoderate pressure.

The operation of my improved pump is as follows: At the outward strokeof the piston, in direction of the arrow L, Fig. I, the inlet-valves a.a will admit the air or gases to the interior of the cylinder. At theend of the outward stroke these valves a a will gently close by means ofthe springs d d. At the return stroke of the piston, and after thepressure of the compressed air or gases has become sufficient-ly strongto overcome the resistance of the spring b, and whatever resistancethere may be resulting from the pressure in the receiver into which theair or gases may be forced, acting on the back side of the outlet-valveD, the valve D will open and permit the compressed gases to escape, and,as shown in Fig. III, the piston C will travel beyond the end of thecylinder, taking the valve D upon and with itself by reason of theyielding of the spring l), thus discharging the entire contents of thecylinder. At the return stroke ofthe piston the valve D Will follow itback to its seat, and an immediate vacuum will be produced as the pistonleaves the valve, which vacuum will again be supplied through the valvesc a, as above described.

What I claim as my invention, and desire to secure by Letters Patent, is

- The eduction-valve D, arranged to yield and operate substantially asdescribed, in combi` nation with a piston, C, and cylinder, F.

THOMAS DOANE. Witnesses:

G. W. LUNT, CEAS. S. LINCOLN.

spiral springs d d,

